Infidelity and the right response

About a week ago, a man who had kept a tab on his wife due to some signs he noticed finally caught her (live!!!) in a hotel with her lover stark naked, doing it. He head butted his wife's lover; the guy no strong at all, he fainted but the wife escaped before her turn. (Meanwhile, the marriage is blessed with 3 lovely kids).I wanna know;(a) Does a man or woman have any right to react violently towards his/her hubby's lover on sighting them 'in action'

(b) Whose 'case' should be addressed??? the hubby or the lover???

A colleague said his reaction would depends on the location the luv birds were caught! What do you have to say...